From a distance of no less than 100 million kilometers, spacecraft Lucy witnessed a lunar eclipse. And that produces very special images.

A total lunar eclipse is always beautiful to see. And last week it was that time again; the earth was just exactly between the sun and the moon, so that temporarily no (direct) sunlight fell on the moon. Unfortunately, the complete lunar eclipse from the Netherlands and Belgium could not be admired; only the beginning of it was visible.

Unique perspective

That is of course a pity. But new images taken by spacecraft Lucy make up for a lot. In the images we see next to the moon, also our own planet (you can even see very well that it rotates). At some distance we can see the moon (which has been made six times brighter in post-processing, so that it can be seen a little better). In the timelapse, however, we see the moon gradually disappear into the shadow of our planet.

L’LORRIE

From a distance of about 100 million kilometers, spacecraft Lucy had a unique view of the whole thing. To capture the lunar eclipse, the probe used its most sensitive camera, called L’LORRI. “While total lunar eclipses aren’t that rare, it’s not that common that you get the chance to observe them from a whole new angle,” said lead researcher on the Lucy mission, Hal Levison. “When the team realized that Lucy had the opportunity to study this lunar eclipse – as part of the process aimed at calibrating all the instruments – everyone was incredibly excited.”

First half

That’s not to say it was easy to capture the images; Lucy was not designed to capture lunar eclipses. The probe has a very different mission: to study Trojans. Trojans are asteroids that orbit the sun in the same orbit as Jupiter. However, the distance between those space rocks and the Sun is five times greater than the distance between the probe and the Sun is currently. That means Lucy had to operate in a much warmer environment to create these images than it was actually designed for. That is why it was also decided to let the probe only capture the first half of the lunar eclipse; Of course, nobody wanted to risk overheating the probe while capturing a fairly “ordinary” lunar eclipse. That is why we no longer see the moon escaping from the shadow of the earth in the images.

The Trojans are divided into two swarms. Both swarms follow Jupiter’s orbit, but one swarm moves ahead of the planet at a fixed distance. And the other swarm moves a fixed distance after Jupiter. Image: NASA/SwRI.

L’LORRIE

Lucy captured the footage using the most sensitive camera on board: L’LORRI. So that camera is designed to capture Trojans. The probe will explore several of these Trojans more closely, and L’LORRI will come in very handy; with the sensitive camera, Lucy should be able to clearly capture the Trojans – despite being very dark – and even spot surface features – such as the somewhat larger craters.

About Lucy

Lucy launched last October and is still en route to Jupiter; it will not be until 2027 that he will admire the first Trojan up close. To get there, Lucy makes clever use of gravity pendulums. In doing so, the probe skims past a planet – in this case Earth – and uses its gravitational field to change both speed and direction, significantly reducing travel time. The next gravitational pendulum is planned for October 2022. Another will follow in December 2024, after which the probe will skim past the asteroid 52246 Donaldjohanson in April 2025. This asteroid is part of the asteroid belt and is therefore not a Trojan; only in 2027 does Lucy skim past the first Trojan: 3548 Eurybates. In the months that follow, Lucy flies past three more Trojans to get another gravitational pendulum off Earth in December 2030 and set course for the last Trojan that—unlike the Trojans Lucy studied in previous years—not for the planet. Jupiter travels out, but at a fixed distance, in the wake of the gas giant orbiting the sun.

wealth of information

Lucy is the first-ever mission to Jupiter’s Trojans, and the mission is expected to yield a wealth of information about the Trojans. It is believed that you can think of those Trojans as leftover building materials identical to the materials from which the outer planets were built billions of years ago. Because the space rocks at such a great distance from the sun have hardly undergone any changes, they are also a kind of time capsules that can provide more insight into the history of our solar system and possibly also tell more about the origin of ingredients for life.

In addition to a wealth of information about those Trojans, we can also look forward to beautiful photos – that is what Lucy has already made of her home planet and surroundings. The snapshots will give us – for the first time – a picture of the surface of these asteroids. L’LORRI will also be used to search for possible ‘moons’ around the asteroids to be studied. And the camera will start hunting for any ring systems around the Trojans. We will undoubtedly hear (and see) a lot more from Lucy!